This invention relates to a light-proof case, containing a radiographic film and chemical products for the development and fixing treatments thereof, intended to be used for carrying out a radiography and for successively treating the film without having to make recourse to a dark room.
Cases of the above type are known and mostly used for the endooral radiography, and they comprise an envelope subdivided into two intercommunicating portions, in one of which a radiographic film is housed, whilst the other portion encloses a single bag made of plastics and containing chemical products in a liquid state for the development-fixing treatment of the film in a monobath, or it encloses two bags containing respectively and separately the chemical production a liquid state for the development and fixing treatments of the film, as well as means for intentionally tearing said bags. A case of this type is used as a support for the film when this latter is introduced into the mouth of a patient for carrying out the radiography, and after the exposure has been accomplished and the case has been extracted from the patient's mouth, the means for tearing the single bag are activated to allow coming out from the bag the chemical products and to let them act on the film in order to carry out the development-fixing treatment, or even said means are activated for tearing the first bag in order to carry out the development treatment of the film, and then they are activated again, after a suitable period of time, for tearing the second bag in order to carry out the fixing treatment.
The main problems in this type of film carrier cases are raised by the means for tearing the bag or bags containing the chemical products. In fact, it is necessary for these means to be absolutely reliable in that they should be incapable of accidentally acting unless they are expressely activated, they should give rise, when activated, to an ample and clean tear of the bags, such as to ensure the coming out therefrom, in a very short time, of the whole quantity of the chemical products contained therein as well as an easy flow of these latter towards the film, and finally they should not introduce difficulties in the indusrial operations by which the components are mounted into the envelope. One or another of these requirements is not sufficiently complied with by the tearing means which have been proposed until now, which are in the form of pins intended to perforate the bags, of strings intended to be pulled from outside the envelope, of patterns intended to guide a tear obtained by pulling in opposite directions the two edges of the bag, or of simple stiffening means inserted into a bag to allow carrying out the tearing by a pulling action exerted onto a part of the bag itself.